What are the Tivoli Storage Manager library manager and library clients in TSM SAN environment

TSM Library Manager and TSM Library Client methods are used in the Tivoli Storage Manager environment where a single Tape Library has to be shared among 2 or more TSM Servers and Storage Agents in a SAN environment. Sharing a tape library means that multiple TSM Servers will use the tape drives of a library for their operations at the same time. Because only one drive can be used by one server at a time, there has to be someone who controls the access to the physical devices.

This is done by serializing the access to the devices. In addition to the control of the devices the library manager also has to control the status, ownership and location of the tape volumes inside the tape library. The library manager is the only Tivoli Storage Manager server with the inventory information of the shared tape library. The library manager is the only Tivoli Storage Manager server who knows all volumes that are inside a library. To learn how to configure Library Manager and Library Client visit this page How to Configure TSM Library Manager and TSM Library Clients in SAN Environment

Tivoli Storage Manager(TSM) Library Manager Overview

The library manager is the only Tivoli Storage Manager server which performs operations to the library. The task of the library manager is to physically control the library. All the communication with the library is done by this server. The library manager will also serialize the access to the tape drives, so that only one server is using a tape drive at the same time.

The checkin and checkout of volumes will be performed by the library manager only. This server is the only server with a library inventory table for that library. The ownership is added to the inventory table to keep track which tape belongs to a certain library client. This is the only server in the environment that knows all the volumes. The library manager can also use the library for its own purposes, without being a library client at the same time.

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TSM Library Manager Operations:

Library initialization 

Since the library manager is the only Tivoli Storage Manager server which interacts with the library, the initialization will be done by this server during the start-up process of the server.

Volume mount/dismount

The library manager can be contacted by the clients which send mount and unmount requests. These requests will be carried out, and afterwards, a response will be sent to the clients.

 Checkin/Checkout Volumes

Only the library manager can checkin and checkout out tape volumes. The clients do not have the right to perform a checkin or checkout command.

 Auditing Library

The library inventory is maintained only on the library manager. The audit process on the library manager checks the presence of the volumes and the actual slot locations.

Tivoli Storage Manager(TSM) Library clients Overview

The library client uses the Library Manager for the handling of the physical hardware. The client send the requests to the library manager, and afterwards reads or writes to the tape drive it was given access to.

To send requests from the library client to the library manager, and to send the response from the manager to the client, the server-to-server communication protocol is used. That means that a TCP/IP connection is necessary and the two Tivoli Storage Manager servers must be configured to each other. In an environment with multiple library clients, there is no need to have each Tivoli Storage Manager server configured to every other Tivoli Storage Manager server, because the communication has always been done directly with the library manager.

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TSM Library Client Operations:

• No library client has access to the library in the same way that it can control the gripper to mount a volume. The library client has to send a request to the library manager, which controls the library and mounts volumes.

• If a new volume is needed the library client sends a request to the library manager. The library manager chooses a scratch tape and updates the ownership of the tape. After doing this a response is send to the client, and the client then can issue a mount request in order to use the volume. 

• If a volume is not used any more, the library client sends a release request to the library manager and the tape will be returned to the scratch pool.

• The audit library operations is used to update the library manager’s inventory information. The library client sends the library manager the name of the tapes it is using, so that the ownership of the tape volume can be updated in the library inventory table of Library Manager.

• The library client has no library inventory table for a shared library. Even so, storage pool volumes can be seen with the query volume command, and database backup volumes can be seen with the query volhistory command. The DRM volumes table can also be queried.

Steps to Follow to Configure TSM Library Manager and TSM Library Clients:

Below table describes the high-level steps involved to configure Tape Library sharing in a Multiple TSM Server Environment. You can get detailed steps in TSM Administrator Guide Book. The most important prerequisites to use this feature is that the library manager must be at a higher Tivoli Storage Manager version than the library clients. For example, a Tivoli Storage Manager 6.3 server cannot be a library client to a Tivoli Storage Manager 6.1 library manager.

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TSM Library Manager Configuration	TSM Library Client Configuration
1) Define a shared library	9) Define the server that is the library manager. Make sure to use the "crossdefine=yes" option of the DEFINE SERVER command.
2) Define the library path.	10) Define a shared library using the same name as the library defined on the library manager. Specify the library manager server name for the PRIMARYLIBMANAGER option.
3) Define the drive(s).	12) Define the device class, making sure to specify the shared library name from step 10.
4) Define the path for the drive(s).	13) Define the storage pool
5) Define device class.
6) Check in your volumes into the library
7) Define a storage pool.
8) Issue the "query status" command to verify "crossdefine "is set ON
11) Define a path between the library client server to each drive using the server definitions that were created as a result of executing step one of the library client configuration.